Dynamic Mechanical Analysis (DMA) is presented for four glassy polymers. Poly(vinyl acetate), poly(vinyl chloride), poly(styrene), and poly(carbonate) were studied as a function of the heating rate using ramp and step heating programs and a constant frequency of 1 Hz. The effect of frequency on the dynamic mechanical parameters was also examined from 0.01 Hz to 10 Hz. The dynamic elastic storage modulus (E'), the dynamic elastic loss modulus (E'') and the tanδ (E"/E') were affected by both the heating rate and the frequency. Apparent activation energies for the glass transition were also determined for the four polymers which were in the range from 98 of 194 kcal/mol.